// Decode side is specced and easier, because we don't need to find
// matches using different criteria; we simply read and map. There are
// two things we need to do 'depending':
//
// We may need to support interleave. We don't really, but it's
// convenient to do it here rather than rebuild the vector later.
//
// Cascades may be additive or multiplicitive; this is not inherent in
// the codebook, but set in the code using the codebook. Like
// interleaving, it's easiest to do it here.
// stage==0 -> declarative (set the value)
// stage==1 -> additive
// stage==2 -> multiplicitive
// returns the entry number or -1 on eof
internal int decode(NVorbis.Ogg.BBuffer b)
{
int ptr = 0;
DecodeAux t = decode_tree;
int lok = b.Look(t.tabn);
if (lok >= 0)
{
ptr = t.tab[lok];
b.adv(t.tabl[lok]);
if (ptr <= 0)
{
return(-ptr);
}
}
do
{
switch (b.Read1())
{
case 0:
ptr = t.ptr0[ptr];
break;
case 1:
ptr = t.ptr1[ptr];
break;
case -1:
default:
return(-1);
}
}while (ptr > 0);
return(-ptr);
}
